Figure drawing method and apparatus for drawings accentuated lines

Abstract

A method fills a polygon and then draws edge lines while inhibiting renewal of only depth data in a depth buffer. Thereafter, a method fills the polygon while inhibiting renewal of only color data in a color buffer. The filling and drawing are performed by applying hidden surface removing processings based upon depth buffer algorithm.

What is claimed is: 
     
       1. A figure drawing method comprising: generating color data corresponding to addresses sequentially generated by line segment generating means;   filling a polygon based upon color data and depth data, by applying hidden surface removing processings based upon a depth buffer algorithm while inhibiting renewal of depth data in a depth buffer and while allowing renewal of color data;   drawing a figure based upon color data and depth data by applying hidden surface removing processings based upon said depth buffer algorithm; and   filling said polygon based upon color data and depth data by applying hidden surface removing processings based upon said depth buffer algorithm while inhibiting renewal of color data and while allowing renewal of depth data in said depth buffer.   
     
     
       2. A figure drawing method as set forth in claim 1, further comprising the step of drawing the figure by applying hidden surface removing processings based upon said depth buffer algorithm with inhibiting of renewal of color data while allowing renewal of depth data in said depth buffer, after   drawing of said polygon by applying hidden surface removing processings based upon said depth buffer algorithm with inhibiting of renewal of color data while allowing renewal of depth data in said depth buffer.   
     
     
       3. A figure drawing method as set forth in claim 1, wherein the figure is at least one edge line of said polygon. 
     
     
       4. A figure drawing apparatus comprising: pixel data generating means for individually outputting first pixel data for filling a polygon which constitutes a three dimensional object, and second pixel data for drawing a desired figure;   linear interpolation means for generating three dimensional coordinates data including plane coordinates data and depth data of a line segment portion of the polygon and of the desired figure based upon said first and second pixel data;   color data generating means for generating color data, based upon said first and second pixel data, said generated color data corresponding to the three dimensional coordinates data generated by said linear interpolation means;   a depth buffer for holding said depth data included in the three dimensional coordinates data generated by said linear interpolation means;   a color buffer for holding the color data generated by said color data generating means;   repetition control means for controlling said pixel data generating means to repeat outputting said first and second pixel data; and   renewal control means for selectively inhibiting renewal of the depth data and renewal of the color data corresponding to the number of time of repetition by said repetition control means.